Fast signal detection and distributed computing in portable computing devices

ABSTRACT

This disclosure describes a distributed reader architecture for a mobile computing device such as cellular telephone handset. This architecture includes a reader library that reads device capabilities and business model parameters in the device, and in response, for selects an appropriate configuration of reader modules for identifying a content item. The reader modules each perform a function used in identifying a content item. The modules are selected so that the resources available on the device and in remote devices are used optimally, depending on available computing resources on the device and network bandwidth. One example of a reader module is a fast watermark detection module that quickly detects the presence of a watermark, enabling resources to be focused on portions of content that are most likely going to lead to successful content identification. A watermark signal structure for fast watermark detection is comprised of a dense array of impulse functions in a form of a circle in a Fourier magnitude domain, and the impulse functions having pseudorandom phase. Alternative structures are possible.

RELATED APPLICATION DATA

This application claims the benefit of U.S. Provisional Application No.60/599,479, which is hereby incorporated by reference.

TECHNICAL FIELD

The invention relates to signal processing and distributing computing,particularly in portable computing devices such as mobile phones.

BACKGROUND AND SUMMARY

Portable computing devices, like mobile phones, are becomingincreasingly more powerful and functional. For example, these devicesinclude cameras, video capabilities, television tuners, audio recordingand playback capabilities, etc. Further, since these devices are alsocommunication devices, they also provide network computing services,like access to the Internet, synchronization of data with other devices,etc.

Despite the increasing functional capabilities and increases incomputing power, there is still significant strain on the computingpower of a small, hand held device. As such, there is a need forenhanced architectures and computing methods that support the vastvariety of functions becoming available while making the best use of thecomputing resources on the device.

One major drain on the computing resources of a mobile phone, forexample, is multimedia signal processing. Examples of applicationsinclude capturing and sending photos, playing music, playing video, etc.One particular application is associating various actions withmultimedia content, such as linking a photo of a product in a catalog ormagazine to a web site providing more information or purchaseopportunities. Another example is linking a picture of musician oradvertisement to an action of downloading a related ring tone to a phoneor downloading related music in streaming mode or file format to amobile phone handset. Implementations of this application are describedin WO00/70585 and U.S. Pat. No. 6,505,160, which are hereby incorporatedby reference.

These types of applications present major challenges for systemdevelopers:

1. how can these applications be implemented in software that runs onthe phone hand set?

2. can these applications be implemented to run efficiently on ahandset?

3. do these applications have unique hardware or software requirementsthat are not currently available on the handset alone?

4. can the application be widely deployed across handsets with differentcomputing platforms, operating systems, and processors? (e.g., somehandsets only execute programs written Java, yet the application may notrun efficiently in Java).

In the network computing world, distributing computing schemes have beendeveloped to take complicated software tasks, break them into modulesand distribute execution of these modules across networked and/orparallel processors. Because of the unique architecture of the mobilephone handset, these schemes may not directly translate to the mobilephone computing architectures now available. As such, there is a needfor new computing schemes and new distributing computing architecturesfor this environment.

The invention provides a reader for content identification and relatedcontent identification methods for mobile computing devices such ascellular telephone handset. One aspect of the invention is a readerincluding a reader library that reads device capabilities and businessmodel parameters in the device, and in response, selects an appropriateconfiguration of reader modules for identifying a content item. Thereader modules each perform a function used in identifying a contentitem. The modules are selected so that the resources available on thedevice and in remote devices are used optimally, depending on availablecomputing resources on the device and network bandwidth.

Additional aspects of the invention are methods for identifying acontent item captured from a mobile telephone handset, as well asmethods for using combinations of signal filtering, watermark detectionand fingerprinting to identify content using a combination of handsetprocessing and server processing.

One example of a reader module is a fast watermark detection module thatquickly detects the presence of a watermark, enabling resources to befocused on portions of content that are most likely going to lead tosuccessful content identification. A watermark signal structure for fastwatermark detection is comprised of a dense array of impulse functionsin a form of a circle in a Fourier magnitude domain, and the impulsefunctions have pseudorandom phase. Alternative structures are possible.

Further features will become apparent with reference to the followingdetailed description and accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram illustrating a mobile device handset and itscommunication with a network.

FIG. 2 is a diagram illustrating an expanded reader architecture thatadapts based on device capabilities and business model parameters.

FIG. 3 is a diagram illustrating interaction between the reader libraryand tables that store parameters that the reader library uses to adaptits operation as a function of device capabilities, time, location,business model, etc.

FIG. 4 is an example of a signal structure in the Fourier magnitudedomain used for fast signal detection.

FIG. 5 illustrates the signal structure of FIG. 4 in the spatial domain.

DETAILED DESCRIPTION

FIG. 1 is a diagram illustrating a mobile device handset 20 and itscommunication with a network. The handset includes a computing platform,including a processor, RAM, and persistent storage. On this platform,the handset processor executes programming instructions in functionalmodules on the device. While a typical handset may have many modules,this particular example shows a user interface 22 and a reader 24.

The user interface controls basic input/output functions, includingreceiving input from the handset's control keys, and providing outputvia a display and audio output device. The reader 24 processesmultimedia input, such as frames of video, still images, and/or audiostreams.

For the purpose of illustrating the operation of the computing platformof our mobile computing device architecture, we focus on the applicationof “connected content.” Connected content refers to associating anaction with content items. For example, the reader receives a contentitem, such as an image from email, the web, or captured from thedevice's camera, and the reader performs a series of actions todetermine an action associated with that content item. This action mayinvolve returning a web page for display, returning web links, playingmusic or video, downloading a ring tone, etc.

In the application of connected content, the reader illustrated in FIG.1 performs a series of operations to compute an identifier (ID) of thecontent item. This identifier is then mapped to an action. This actionis specifically represented in FIG. 1 as the return of a URL, which mayrepresent a web page or some other network service delivered to thehandset.

The handset communicates with a network 26 (e.g., an Internet Protocolnetwork) via its built in mobile network connectivity system, which maybe based on any of a variety of mobile communication technologies (e.g.,3G, GSM, CDMA, bluetooth, and combinations thereof). Within thisnetwork, there are various servers responsible for providing variousservices for handset users. These servers may include servers operatedby the mobile telephone service provider, one or more Internet serviceproviders, web servers on the Internet, content services, etc.

The challenge for this type of application is developing an efficientmechanism for mapping the content item to its corresponding actionacross different types of devices with varying software and hardwarecapabilities, and across different mobile telephone service providerswith varying business models.

FIG. 2 is a diagram illustrating an expanded reader architecture thatadapts based on device capabilities and business model parameters. Thedevice capabilities may be fixed parameters, such as a particular typeof processor, memory, signal processing modules (like optimized FFTmodule). They may also be variable, such as available computing cyclesthat vary with processing load and fluctuations in available bandwidthfor transmitting content items to other processors (e.g., either networkservers or neighboring devices connected via Bluetooth or otherconnections). The business model parameters also control computing byfavoring certain types of operations over others to advance a desiredbusiness model. For example, it may be advantageous to use morebandwidth by sending content via the mobile service provider to adistributing computing resource rather than attempting to use only localcomputing resources on the handset. Other related parameters includelocation based services that vary based on location of the handset(e.g., determined by triangulation in the mobile phone network or viaGPS hardware). The time of day and availability of processing resourceson other connected devices may also control the reader operation.

To be adaptable, the reader is subdivided into modules that break downthe reader application into functional blocks that can be executedseparately, possibly in parallel and possibly taking advantage ofdistributed computing through mechanisms like Remote Procedure Calls tofunctions executing on other devices. The reader library 40 is a modulethat controls operation based on the device and business modelparameters.

In this particular example, the reader library selects the combinationof modules that are suited for the device and business model. The readerapplication process is divided into functions, such as filter 40, fastdetect 42, fingerprint 44, and full detect 46. Each of these modules canplay a role in the reader application process of receiving a contentitem and converting that content item into an action. Depending on thedevice and business model parameters, the reader library selects themodules on the handset that will participate. The rest of the functions,if any are left, are performed on one or more remote devices asexplained below.

Depending on the selection of the reader library, part of the readerprocess is executed on the handset, and part is executed on a remotedevice (or multiple remote devices). As shown in box 50, the nature ofthe data sent from the reader to a remote device depends on whichfunctions of the reader process are executed on the handset. In onescenario, the reader sends the content item (e.g., frames or blocks ofan image or an audio clip) to a remote device for determination of itsID. This uses minimal resources on the handset, but consumes morebandwidth.

In another scenario, the filter 42 filters the content item leaving onlycomponents of the content necessary to complete the remaining contentidentification tasks. Examples of this type of filtering are describedin U.S. Pat. Nos. 6,724,914 and 6,483,927, which are hereby incorporatedby reference. Pre-filters used for digital watermark detection aredescribed further below. Pre-filtering uses more processing resources onthe handset and less bandwidth.

In another scenario, the handset performs a fast detect 42 to quicklyidentify whether a content item includes a digital watermark signal, andto provide registration information (so that the content can be alignedfor further ID extraction through fingerprint analysis or digitalwatermark message extraction). There are several possible ways toimplement fast detect. Some examples are described below. If the contentidentification is performed using some other machine readable code otherthan a digital watermark (e.g., a bar code or other visible machinesymbology), the fast detect can be used to quickly identify the presenceand location of the machine readable symbology.

In the case of the fast detect, the handset sends only blocks of content(e.g., filtered and/or geometrically registered, and/or withregistration parameters) for which a fast detection has identified thepresence of a code signal. This may consume more processing resources onthe handset, but uses less bandwidth than sending all or substantialparts of the content to a remote device for identification.

The fast detect may also be used in conjunction with a fingerprintidentification scheme where the fast detect provides registrationparameters that facilitate accurate computation of the contentfingerprint. The content fingerprint is a form of robust hash that ismatched against a database of fingerprints to identify the content item.

In another scenario, the handset computes the content item's fingerprintusing a fingerprint module. There are a variety of content fingerprintschemes available for video, audio and images. One type offingerprinting process is to hash features of the content, such asfrequency domain features, to compute a vector of hashes that are thenmatched with corresponding vectors of hashes in a fingerprint database.Once a match is found, the database returns a content identifier. Inthis scenario, the handset computes the fingerprint, and sends it to adatabase for content identification.

Finally, another scenario is to perform a full detect using a fulldetect module 46. This approach is premised on the existence of anidentifier in machine readable form in the content item. This mayconstitute a digital watermark, bar code or other machine readable code.In this case, the handset uses the most processing resources and theleast bandwidth because it does all the work necessary to identify thecontent item and only sends a small identifier to the network.

In the case where a URL represents the action to be performed, a deviceon the network looks up the identifier in a database and returns thecorresponding URL to the handset. The action need not be represented bya URL. It can be some other process for returning programming or contentto the handset or some device associated with the handset owner. Forexample, the database may return the name of an action, which in turn,triggers a server in the network to perform that action, either alone,or combination with other servers or devices. The action may includesending a video, music or image file, executing an electronic purchasetransaction, downloading content or programming to the handset, etc.

FIG. 3 is a diagram illustrating interaction between the reader libraryand tables that store parameters that the reader library uses to adaptits operation as a function of device capabilities, time, location,business model, etc. In the illustration, the parameters used to controlthe reader library's selection of modules are represented in twotables: 1. A Device Capabilities Table, and 2. A Business Model Table.The first column in the device table lists device capabilities, like theprocessor type, the operating system, the existence of any specialprocessing features that assist in signal processing like an FFT module,memory, memory bandwidth, network bandwidth, connection speed, andlocation service availability. This table acts as a registry of theavailable capabilities. Some of these capabilities are fixed, such asthe processor; and others are variable depending on external conditions,such as the network bandwidth and connection speed. If a capability ispresent, then the items in the row corresponding to the capability arechecked. The columns represent different possible configurations of thereader process, such as: “Extract ID on handset”, “Extract ID on server”and “Distribute reader process between handset and server According toBandwidth.” In the latter example, the reader process adapts based onavailable bandwidth such that more processing is distributed to theserver when more bandwidth is available.

The reader process may also adapt based on available computationalcycles depending on other applications running on the handset at aparticular time. If other higher priority applications are running,reader process functions are off loaded to the server.

The Business Model interacts with the reader library module in a similarway. The reader process can be configured differently based on, forexample, the service provider, the calling plan for the phone, the timeof day (use less bandwidth when bandwidth is more expensive to the useror provider), the ability of the service provider to manipulate images,video or audio on its or its partners' servers, etc. The reader processcan also be adapted for different ISPs and web services that areavailable. For example some web services may support location basedservices, while others may not. Location based services enable theaction performed in response to content identification to be tailoredfor the handset's location. Some providers may support ring tonedownloading while others may not. There are many possible options, andthe reader library can adapt depending on the settings in both thedevice and business model tables.

Distributed computing of the reader process is not limited tohandset-server. Some handsets support bluetooth or other wirelessconnections to devices with additional processing power. Parts of thereader process can also be distributed to devices with range of abluetooth connection, such as the user's home PC or other computingdevice.

Distributed processing can be implemented using Remote Procedure Calls.For example, the handset can make a call to a fingerprint module on aserver and pass it a block of content. In response, the fingerprintmodule returns an ID, which is then mapped to an action.

Several processing threads can be spawned in parallel. For example, animage frame can be broken into blocks, each with its own reader processthat is distributed between the handset and one or more remote devicesnetworked with the handset. Once an ID is found or an action iscorrectly mapped to a content item, all concurrent reader processes arecanceled. This is particularly useful when a stream of video framescaptured by the handset camera are input to the reader library. In thiscase, the reader library distributes the reader process, frame by frameor block by block. The filter and fast detect blocks can be used topre-process blocks of content before they are processed further for IDextraction. As explained below, the fast detect module can be used toweed out content that is unlikely to lead to a successful ID extraction.

The computing architecture described above can be used for otherresource intensive processes to enhance the capability of mobile phonehandsets. Below, we continue with the example of the reader application,and provide more information and digital watermarking andfingerprinting.

Digital Watermarking

Digital watermarking is a process for modifying physical or electronicmedia to embed a hidden machine-readable code into the media. The mediamay be modified such that the embedded code is imperceptible or nearlyimperceptible to the user, yet may be detected through an automateddetection process. Most commonly, digital watermarking is applied tomedia signals such as images, audio signals, and video signals. However,it may also be applied to other types of media objects, includingdocuments (e.g., through line, word or character shifting), software,multi-dimensional graphics models, and surface textures of objects.

Digital watermarking systems typically have two primary components: anencoder that embeds the watermark in a host media signal, and a decoderthat detects and reads the embedded watermark from a signal suspected ofcontaining a watermark (a suspect signal). The encoder embeds awatermark by subtly altering the host media signal. The readingcomponent analyzes a suspect signal to detect whether a watermark ispresent. In applications where the watermark encodes information, thereader extracts this information from the detected watermark.

Several particular watermarking techniques have been developed. Thereader is presumed to be familiar with the literature in this field.Particular techniques for embedding and detecting imperceptiblewatermarks in media signals are detailed in the assignee's U.S. Pat.Nos. 6,122,403 and 6,614,914, which are hereby incorporated byreference.

Pre-Filtering for Signal Detection

In signal detection, and particularly digital watermark detection, apre-filter may be used to de-correlate the signal being sought from thehost signal. In particular for a digital watermark detector, a filter isused to de-correlate the digital watermark from the host signal.

One example of this type of de-correlating filter for digital imagewatermarks operates as follows. For each image sample, it compares thesample with each of its eight neighboring image samples. The filterreplaces the value at the center sample with a value that is incrementedeach time the center sample value is greater than a neighbor value anddecremented each time the center sample is less than the neighbor value.In particular, for each comparison, the filter increments by a value of1 if the center sample is greater than its neighbor, it increments by avalue of −1 if the center sample is less than its neighbor, and makes nochange otherwise. The output of the filter will be between −8 and +8when an eight neighborhood (3 by 3 sample region) is used in the filterimplementation. Such type of a filter has a number of applications suchas edge detection, signal enhancement, etc. in signal processing andoperates on different media types (image, video and audio) and samplesin various domains. For digital watermark applications, it may be usedto estimate the original host signal and watermark signal, where thewatermark signal is applied as an additive, antipodal PN signal.

The filter discussed in the previous paragraph may be implemented invariety of ways. One particular implementation makes comparisons betweenthe center sample and each neighboring sample, and transforms the resultof this comparison to an increment or decrement value (e.g., +k or −k,where k is a constant like 1, 2, 3, etc.). The filter sums each of theincrement/decrement values from each neighbor, and then replaces thecenter sample value with the result of the summation. This type offilter can be implemented efficiently using a look up table. Forexample, the comparison operation is performed by subtracting the centersample value from a neighbor sample value to produce a difference value(−255 to +255 for an 8 bit sample). The result is then fed to a look-uptable, which maps the difference value to an increment/decrement valueand outputs that value. The filter sums the look-up table output foreach neighbor in the neighborhood, and replaces the center sample withthe result of the summation. This neighborhood may be the eightneighbors in 3 by 3 block of samples, the adjacent samples in aone-dimensional signal, the horizontally and/or vertically adjacentneighbors in a two or more dimensional signal, etc. The size of theneighborhood may be increased as well. The look-up table may be used toimplement a variety of non-linear filters efficiently.

Fast Signal Detect

Very fast (computationally inexpensive) detection of the presence of adigital watermark signal is highly desired. Some existing digitalwatermark detectors employ 2D FFT, log-polar mapping and log-polarcorrelation for detecting the watermark signal and its registrationparameters (e.g., rotation, scale, translation). The emphasis of fastdetection is on alternative watermark signal designs and techniques thatuse substantially less processing than currently necessary fordetermining the presence of an embedded watermark signal.

A digital watermark may comprise several signal components, including acomponent used for fast detection and registration, a component for moreaccurate registration, and a component for conveying a variable message.These components can be integrated together or totally separate. Forexample, a signal component used for detection may also convey variablemessage bits. In this discussion, we focus on digital watermarkstructure design used for detection and registration. These watermarkstructures may also convey variable data, but this variable datacarrying function is not the focus of this section. The patentsincorporated above and the watermarking literature describe variousschemes for conveying hidden data in digital watermarks.

FIG. 4 illustrates a watermark signal structure in the Fourier Magnitudedomain enabling fast detection and registration information. Thewatermark structure in FIG. 4 includes a dense full circle in thefrequency domain. This circle is made up of individual impulse functions(e.g., sine waves) with pseudorandom phase with respect to each other. Afull circle is an excellent candidate for fast detection. Detection ofthis structure exploits the fact that for a circle in the 2D Fourierdomain, a slice through any axis (irrespective of rotation or scale)passing through DC is a pair of symmetrical points.

Projection of the 2D FFT onto 1 dimension (either X or Y axis) providesa fast mechanism to detect the presence of this signal. Presence of thesignal is detected by pre-filtering an image block (as explained in theprevious section) followed by 1D FFTs along each row, and summing theFFTs across rows to obtain the projection. Detection of a strong peak inthe 1D projection indicates the presence of the watermark. Note thatdetection includes filtering, 1D FFTs, and peak finding in the 1D FFT,which can be computed in a more efficient manner than techniquesrequiring multiple 2D FFTs.

FIG. 5 shows the spatial domain representation of the dense circle inFIG. 4. The phases are randomized so that the signal can be embeddedinto an image in a substantially imperceptible manner. Techniques forhiding this type of signal in a host image are described in U.S. Pat.No. 6,614,914, incorporated above. For example, a perceptual mask can beused to adjust the watermark signal as a function of the data hidingcapability of a host image. In addition, the signal can be embedded in acolor channel that is less perceptible to humans, such as the yellowchannel.

Detection of Watermark Signal Presence

This section describes a number of alternative methods for quicklydetecting the presence of the watermark signal structure shown in FIGS.4-5. Methods 1-4 are different approximations to the actual 1Dprojection or 1D slice through the 2D transform and differ incomputational complexity. Method 1 is the least expensive.

Method 1

Apply a 1D pre-filter on each row in the block (similar to 2D filterdescribed in pre-filtering section above, but only performed on samplesalong a row)

-   -   Sum all rows in the block    -   Compute 1D FFT magnitude    -   Detect peaks

Method 2

-   -   Apply 2D pre-filter to block    -   Sum all rows in the block    -   Compute 1D FFT magnitude    -   Detect peaks

Method 3

-   -   Apply a 1D pre-filter on each row in the block    -   Compute 1D FFT magnitude of each row    -   Sum row FFT magnitudes    -   Detect peaks

Method 4

-   -   Apply 2D pre-filter to block    -   Compute 1D FFT magnitude of each row    -   Sum row FFT magnitudes    -   Detect peaks

Method 5

-   -   Apply 2D pre-filter to block    -   Compute 1D FFT of each row    -   Sum row FFTs    -   Compute magnitude of sum    -   Detect peaks        Advantages of Fast Detection

Fast watermark detection provides the ability to quickly ascertainwatermark presence in computationally challenging environments such ascell phones and low-end devices. This can result in faster and morereliable overall detection

In server side detection, the fast detection process could be run on theclient to identify signal-bearing image frames to be transmitted to theserver. Using fast detection at the client side, the probability of notdetecting at the server can be reduced. Only those frames in which fastdetection is successful are transmitted to the server.

In client side detection, fast detection can be used to quickly discardframes that do not bear the watermark signal, rather than go through theentire registration and decoding processes. Frames in which the grid isdetected are taken through subsequent watermark detection stages.

Fast detection is also useful in situations where it is necessary toquickly identify regions of interest for watermark detection. Additionalprocessing resources can then be focused on particular regions of thesignal where complete and accurate watermark reading is most likely.

Obtaining Registration Parameters

Although the full circle structure is primarily designed for fastwatermark detection, it has interesting properties that can be exploitedto provide registration parameters (i.e., synchronization).

1. The location of a peak relative to the x and y axes of the 2D FFTprovides scale. Namely, the distance of the peak from the DC point inthe x and y directions provides the scale in these directions.

2. When the distance of the peaks are computed for both the x and y axesas in 1, the location of the peaks also provides an indicator ofdifferential scale.

3. Fitting an ellipse to the circle in the frequency domain (refer tothe elliptical curve fitting technique in U.S. Pat. No. 6,483,927,incorporated herein) can help recover an affine transformation exceptrotation.

4. Rotation can be recovered either by exploiting the phases or byadding a few random impulse function points in addition to the densecircle.

Another approach to obtain registration parameters would be to use thefull circle signal in the Fourier Magnitude domain in addition to acollection of other impulse functions. The full circle can provide fastdetection and ability to recover from large differential scales, whereasthe collection of other impulse functions can help recover any remainingparameters. See U.S. Pat. No. 6,614,914 for the use of a log polartransform to compute registration parameters from a collection ofimpulse function in the Fourier Magnitude domain.

Alternative Watermark Signal Design Choices

The dense circle is just one example of a signal that can be detectedusing the ID projection. Other designs can be selected to reducevisibility of the signal in the spatial domain and make it easier toobtain other registration parameters. For example,

-   -   1. Concentric arcs    -   2. Non-symmetric arcs    -   3. Square centered at DC    -   4. Rhombus (or parallelogram) centered at DC    -   5. Signal designed such that there is an impulse function point        at each possible rotation angle from 0 to 180 degrees. In this        design, each point can be located at a unique radial distance        from DC.    -   6. Multiple lines (not passing through DC) with different slopes        in each quadrant.        Other Types of Fast Detection

The watermark signal (or other ID carrying signal) can be designed withdistinct attributes that facilitate fast detection. These include uniquecolors, unique line structures, unique halftone screening structuresused in printing (e.g., a unique screen angle or frequency), uniquefrequency content, a unique signature in the signal's histogram, etc.The fast detector is then tuned to measure evidence of these attributes,and if sufficiently present, direct further detection activities at theregion where these attributes are found.

The Fast Detector as Positive Feedback

The fast detector enables the handset to display or emit a sound whenthe handset is close to capturing an image with a readable watermark (orother code signal). For many users, it may be difficult to position thehandset's camera at the proper angle and distance from a watermarkedobject, leading to frustration. However, if the fast detector isconstantly running on image frames captured while the handset is moving,the positive feedback from detection of the watermark signal can helpguide the user to the correct location and orientation of the camera toensure accurate watermark recovery. The user can then be instructed viaa beep or light emitted by the handset to press a capture button toensure that the image being captured is likely to contain a recoverablewatermark signal.

Fingerprint Configurations

Below, we list several alternative approaches for using fingerprints,possibly in conjunction with fast detection of a watermark, to performcontent identification on mobile computing device.

Approach 1

On capturing the image using the cell phone, calculate its fingerprint(i.e., some form of robust digital signature). Send the fingerprint tothe server where it is matched with fingerprints in a database toidentify the captured material. Further action can then be taken basedon the ID returned by the database.

Approach 2

Similar to approach 1 except that instead of calculating thefingerprint, the image is sent to the server where it is matched(correlated) directly with a database of stored images.

Approach 3

Same as approach 1 except that a watermark template is embedded in theprinted material to provide synchronization. Synchronization improvesrobustness of fingerprint extraction and matching because it allows thefingerprint to be computed after the content is aligned using theregistration parameters from the synchronization process.

Approach 4

Same as approach 2 except that a template is embedded to providesynchronization. Synchronization simplifies/improves the task ofmatching with the database of images.

Approach 5

A payload message signal can additionally be used in approaches 3 and 4,making the system more robust. In other words, the system could rely oneither the watermark or the fingerprint or both.

These scenarios are examples of alternative configurations that thereader library can select to adapt handset performance based on thedevice and business model parameters.

Concluding Remarks

Having described and illustrated the principles of the technology withreference to specific implementations, it will be recognized that thetechnology can be implemented in many other, different, forms. Toprovide a comprehensive disclosure without unduly lengthening thespecification, applicants incorporate by reference the patents andpatent applications referenced above.

The methods, processes, and systems described above may be implementedin hardware, software or a combination of hardware and software. Forexample, the auxiliary data encoding processes may be implemented in aprogrammable computer or a special purpose digital circuit. Similarly,auxiliary data decoding may be implemented in software, firmware,hardware, or combinations of software, firmware and hardware. Themethods and processes described above may be implemented in programsexecuted from a system's memory (a computer readable medium, such as anelectronic, optical or magnetic storage device).

The particular combinations of elements and features in theabove-detailed embodiments are exemplary only; the interchanging andsubstitution of these teachings with other teachings in this and theincorporated-by-reference patents/applications are also contemplated.

1. A reader for a mobile telephone handset comprising: a reader library for reading device capabilities or business model parameters and in response, for selecting a configuration of reader modules for identifying a content item; and reader modules, each for performing a function used in identifying a content item.
 2. The reader of claim 1 wherein the reader modules include a pre-filter to provide a filtered signal used for identifying the content item from a host signal captured on the handset.
 3. The reader of claim 2 wherein a content fingerprint is derived from the filtered signal, and the fingerprint is used for identifying the content item.
 4. The reader of claim 2 wherein the pre-filter is executed on the mobile telephone handset and identifying the content item from the filtered signal is performed on a device remote from the handset.
 5. The reader of claim 2 wherein the reader modules include a digital watermark detection module for identifying the content item based on a watermark extracted from the host signal.
 6. The reader of claim 1 wherein the reader modules include a fast detect module and a full detect module used for identifying the content item from a host signal captured on the handset.
 7. The reader of claim 6 wherein the fast detect module is executed on the handset and the full detect module is executed on a device remote from the handset to identify the content item.
 8. The reader of claim 1 wherein the reader modules include a fingerprint module for computing a hash of a host signal captured on the handset for identifying the content item from the host signal.
 9. The reader of claim 8 wherein the reader modules include a digital watermark detector.
 10. The reader of claim 9 wherein the digital watermark detector and fingerprint module operate on the host signal for identifying the content item from a host signal captured on the handset.
 11. The reader of claim 1 wherein the device capabilities or business model parameters comprise processor capabilities.
 12. The reader of claim 1 wherein the device capabilities or business model parameters comprise parameters associated with a service provider or calling plan for wireless communication.
 13. The reader of claim 1 wherein the device capabilities or business model parameters comprise network bandwidth available to the handset.
 14. A method for identifying a content item from a host signal captured on a mobile telephone handset, the method comprising: in a server, receiving data derived from the host signal for use in identifying the content item, an identification method being selected from among alternative identification methods based on device capabilities or business model parameters of the handset; in response to receiving the data in the server, identifying the content item from the data according to the selected identification method; and determining an action associated with the content item.
 15. The method of claim 14 wherein the action includes returning data associated with the content item for rendering on the handset.
 16. The method of claim 14 wherein the identification method is selected based on processor capabilities of the handset.
 17. The method of claim 14 wherein the identification method is selected based on a business model parameter relating to a wireless service provider or plan.
 18. A watermark signal structure on a tangible medium for fast watermark detection, the structure comprising: a dense array of impulse functions in a form of a circle in a Fourier magnitude domain, the impulse functions having pseudorandom phase.
 19. A method for detection of an embedded signal in an image signal, the method comprising: receiving an image signal including an embedded array of impulse functions in a frequency domain of the image signal; computing a frequency domain transformation of the image signal; computing a one dimensional projection of the frequency domain transformation; and detecting a peak in the projection to detect the embedded array of impulse functions.
 20. The method of claim 19 wherein the embedded array of impulse functions form a circle in a Fourier magnitude domain, and the impulse functions have pseudorandom phase. 